[DevTools] Initial implementation of device modes.

Source/devtools/front_end/common/Geometry.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 346 matching lines @@
  * @return {!Size}
  */
 Size.prototype.addHeight = function(size)
 {
     return new Size(this.width, this.height + (typeof size === "number" ? size : size.height));
 };
 
 
 /**
  * @constructor
+ * @param {number} left
+ * @param {number} top
+ * @param {number} right
+ * @param {number} bottom
+ */
+function Insets(left, top, right, bottom)
+{
+    this.left = left;
+    this.top = top;
+    this.right = right;
+    this.bottom = bottom;
+}
+
+Insets.prototype = {
+    /**
+     * @param {?Insets} insets
+     * @return {boolean}
+     */
+    isEqual: function(insets)
+    {
+        return !!insets && this.left === insets.left && this.top === insets.top && this.right == insets.right && this.bottom == insets.bottom;
+    }
+}
+
+
+/**
+ * @constructor
  * @param {!Size=} minimum
  * @param {?Size=} preferred
  */
 function Constraints(minimum, preferred)
 {
     /**
      * @type {!Size}
      */
     this.minimum = minimum || new Size(0, 0);
 
@@ skipping 51 matching lines @@
 /**
  * @param {!Constraints|number} value
  * @return {!Constraints}
  */
 Constraints.prototype.addHeight = function(value)
 {
     if (typeof value === "number")
         return new Constraints(this.minimum.addHeight(value), this.preferred.addHeight(value));
     return new Constraints(this.minimum.addHeight(value.minimum), this.preferred.addHeight(value.preferred));
 }